Thousands of Iranian protesters defied threats of a severe crackdown on Thursday, taking to the streets on the 10th anniversary of the 1999 student demonstrations.

Braving batons and tear gas, they chanted "death to the dictator" and set up burning barricades, reports the Associated Press. Tehran's governor promised to "smash" anyone who dared show up. Witnesses told the AP that they saw security forces beating protesters with clubs on Valiasr Street, a major thoroughfare.

Thursday's rally broke a nearly two-week stretch of quiet after a series mass protests against the official June 12 election results. This resurgence heightens speculation that this is a movement that will not be easily quelled – even by the state's heavy hand.

This uprising marks the "most profound challenge" to the Iranian regime since the 1979 revolution that brought it about, says veteran journalist and Iran expert Robin Wright.

The Monitor made a similar statement at the time of the 1999 protests, which ended without bringing about real change. But whereas those protests included only one sector of society, this movement is much more diverse, says Ms. Wright.

"In 1999, the movement ... was a body without a head, without a strategy and without a cause that could mobilize other sectors of society," says Wright, now a public policy scholar at the Woodrow Wilson center in Washington.

By contrast, she points out, this movement is driven by a diverse coalition including two former presidents, a former prime minister, the Islamic world's most politically active women, ethnic minorities, sanctions-strapped businessmen, taxi drivers, famous filmmakers, and members of the national soccer team.

Such coalitions were a key part of the three major changes in 20th-century Iran, including the 1905-11 constitutional revolution, the 1953 Mossadeq period, and the 1979 revolution.

But Wright cautions that this movement, however diverse, is not looking to bring about another revolution.